The basis for the animated film "Porco Rosso" is the all watercolor manga "Hikoutei Jidai" which spans 15 pages. This manga was serialized in the monthly magazine Model Graphix, as a part of Miyazaki's "Zassou Note" series. Miyazaki's fondness for old planes is manifested in "Hikoutei Jidai" and it showcases heavily modified planes from the 1920s along with technical details about them. The manga also features good-hearted and silly men who are devoted to these planes.
Compared to the anime adaptation, the manga has a lighter and more comical tone. It omits Porco's past as a retired Italian Air Force pilot and doesn't delve into conflicts with the fascist government, though there are references to the rise of fascism and opposition against it. Furthermore, the manga doesn't include Gina, and Porco is portrayed as contented. Despite these differences, the anime retains the essence and charm of the original story.
Miyazaki acknowledged that he was unable to fully capture the scale of the life-or-death air battle between Porco and Donald Chuck unlike in animation, and instead relies on the readers' imagination. At the time, little did anyone know that this scene would come to life on the big screen as "Porco Rosso."
